The mechanisms of optic nerve disease are under investigation with experimental models in primates. Glaucomatous damage to the optic nerve is being investigated by studying the effects of elevated intraocular pressure on axonal transport, blood flow, and oxidative metabolism in the optic nerve head. Pertinent anatomic studies of the glia, blood vessels, and nerve fiber bundles are also being done. Histologic and angiographic methods are being used to study optic atrophy of the descending and ascending types. Simiar studies on the effects of intracranial pressure are being conducted to explore the mechanisms of papilledema.